Recently, printing apparatuses using inkjet recording method, such as inkjet printers and inkjet plotters, have been widely used in not only printers for general consumers, but also industrial purposes, such as manufacturing of color filters for forming electronic circuits and for liquid crystal displays, and manufacturing of organic EL displays.
In the printing apparatus using the inkjet method, liquid discharge heads for discharging liquid are mounted as a printing head. For this type of print heads, thermal head method and piezoelectric method are generally known. That is, in the thermal head method, a heater as a pressing means is installed in an ink path filled with ink, and the ink is heated and boiled by the heater. The ink is discharged as liquid drops through an ink discharge pore by pressing the ink with air bubbles generated in the ink path. In the piezoelectric method, ink is discharged as liquid drops through the ink discharge pore by subjecting a part of the wall of the ink path filled with the ink to bending displacement by a displacement element, thereby mechanically pressing the ink in the ink path.
The liquid discharge head can be classified into serial method in which recording is carried out while moving the liquid discharge head in a direction (main scanning direction) orthogonal to a transport direction of a recording medium (sub scanning direction); and line method in which recording is carried out on a recording medium transported in the sub scanning direction in a state where the liquid discharge head being longer in the main scanning direction than the recording medium is fixed. The line method has an advantage of permitting high speed recording because unlike the serial method, there is no need to move the liquid discharge head.
Even with the liquid discharge head of either the serial method or the line method, it is necessary to increase the density of the liquid discharge pores for discharging the liquid drops which are formed in the liquid discharge head, in order to print the liquid drops with high density.
For example, there is known a liquid discharge head constructed by stacking a path member with a manifold (shared flow path) and liquid discharge pores respectively connected to the manifold through a plurality of liquid pressing chambers; and an actuator unit with a plurality of displacement elements which are respectively disposed to cover the liquid pressing chambers (refer to, for example, patent document 1). In this liquid discharge head, the liquid pressing chambers respectively connected to the plurality of liquid discharge pores are arranged in a matrix shape, and the ink is discharged from the individual liquid discharge pores by displacing the displacement elements of the actuator unit disposed to cover the liquid discharge chambers, thus permitting printing at a resolution of 600 dpi in the main scanning direction.